In circular knitting machines, especially those of the multifeed type, pattern means is frequently employed and one form thereof known as a jacquard mechanism employs several units spaced about the machine, each of which comprises a drum, a flexible pattern strip, and selectors with one selector at most for each needle or instrumentality. These pattern strips in endless or belt form have perforations punched therein in rows which align with slots in the drum and the pattern strip is advanced with the drum by sprocket teeth on the latter engaged in corresponding sprocket openings at the pattern strip edges. The selectors in the form of levers have spring pressed pins which either ride on the pattern strip surface or enter a perforation therein and thus read the pattern. As a result, they convey the pattern dictates to rackets by means of a selector cam which exerts a force on the activated levers which in turn rotate said rackets about their axes. The rackets, upon activation, raise the needles either directly or through jacks. To alleviate the force required by the selector cam to exert on the levers in raising the jacks and/or needles, it is of common practice to allow the rackets to raise the jacks and/or needles to a predetermined height, and then to provide a raising cam which will further raise the jacks and/or needles to their desired final heights. An example of one form of such a mechanism according to the prior art is evident in U.S. Pat. No. 2,786,343.
While the mechanisms previously used for needle height selection serve very well for the most part, they are strictly limited in being able to select between only two needle heights. According to this invention, means are provided to allow and specify three needle heights for each needle at every possible activation of the needle.